File operation task optimization

ABSTRACT

A method includes receiving, by a data processing apparatus, a plurality of file operation requests, each file operation request including a priority, a deadline, and an operation type and representing a request to perform an operation on at least one file maintained in a distributed file system; identifying, by the data processing apparatus, a group of file operation requests to be executed together from the plurality of file operation requests, the identification based at least in part on at least one of: the file operations in the group of file operations being directed to a same storage system, or file operations in the group of file operations sharing a common operation type; and sending a request to execute the group of file operation requests to a system configured to perform the group of file operation requests.

CLAIM OF PRIORITY

This application is a continuation of U.S. application Ser. No.15/266,177, filed on Sep. 15, 2016, which is a continuation of U.S.patent application Ser. No. 14/089,588, filed on Nov. 25, 2013, theentire contents of each are hereby incorporated by reference.

BACKGROUND

This specification relates to optimizing file operation tasks indistributed systems.

A distributed system is a collection of networked computing devices or“nodes” working together to perform a computing task. In some cases, thecomputing task may involve analyzing a large amount of data by breakingthe data into small chunks that can be handled in parallel by the nodes.The computing task may also involve storing large amounts of data in anefficient and fault tolerant manner. One system for performing such atask is a distributed file system.

Distributed file systems allow file data to be stored across differentnodes. The system may store multiple copies of the data on differentnodes so that the failure of a single node will not lead to loss orunavailability of the file data. In some cases, a distributed filesystem may allow clients to perform operations similar to those providedby a standard local file system, such as, for example, copying,deleting, and merging files. The clients may perform these operations byissuing file operation requests to nodes of the distributed file system,either directly or through a management application associated with thedistributed file system.

SUMMARY

The subject matter of this application relates to optimizing fileoperation tasks in distributed systems through task clustering anddivision.

In general, one innovative aspect of the subject matter described inthis specification can be embodied in methods that include the actionsof receiving, by a data processing apparatus, a plurality of fileoperation requests, each file operation request including a priority, adeadline, and an operation type and representing a request to perform anoperation on at least one file maintained in a distributed file system;identifying, by the data processing apparatus, a group of file operationrequests to be executed together from the plurality of file operationrequests, the identification based at least in part on at least one of:the file operations in the group of file operations being directed to asame storage system, or file operations in the group of file operationssharing a common operation type; and sending a request to execute thegroup of file operation requests to a system configured to perform thegroup of file operation requests. Other embodiments of this aspectinclude corresponding systems, apparatus, and computer programs,configured to perform the actions of the methods, encoded on computerstorage devices.

Particular embodiments of the subject matter described in thisspecification can be implemented so as to realize one or more of thefollowing advantages. By grouping file operation requests according tothe techniques described herein, greater efficiency and performance maybe achieved in a distributed file system. Overhead, such as networkcommunication costs, associated with multiple file operation requestsmay be reduced, which may lead to increased system performance andthroughput. Further, response time for file operation requests may bereduced as a higher volume of requests may be serviced at a higher ratethan previous techniques.

The details of one or more embodiments of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages of thesubject matter will become apparent from the description, the drawings,and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an environment in which file operation taskoptimizations occur.

FIG. 2 is a block diagram of an example index of file operation tasksused for file operation task optimization.

FIG. 3 is a flow diagram of an example process for file operation taskoptimization through request clustering.

FIG. 4 is a flow diagram of an example process for file operation taskoptimization through request clustering.

FIG. 5 is a block diagram of an example computing device.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

The present disclosure relates to optimizing the scheduling of fileoperation tasks in a distributed file system.

Generally, file operation scheduling involves treating file operationsas stand-alone tasks and scheduling a worker (e.g., a thread, process,and/or other processing resource, which is generally referred to as a“worker”) to execute the tasks one at a time. Tasks are schedulingwithout considering the properties of the associated file operation,such as operation type, source, target, and/or other properties.

The present disclosure describes systems and methods for optimizing thescheduling of file operation tasks in a distributed file system bytaking into account properties of the file operations to be executed. Insome implementations, the execution of file operation tasks is managedin one or more file request managers. The systems may cluster fileoperations to reduce remote process call (RPC) or other communicationoverhead to nodes of an external file system on which the file operationtasks will execute. For example, a file request manager may determinethat two “file copy” task requests may be issued together to theexternal file system in a single request. Issuing both task requests ina single request instead of two separate requests allows overheadassociated with the extra request to be avoided. When higher degrees ofclustering are obtained (e.g., more than two task requests clusteredtogether) the overhead savings increases.

File operations can also be divided to improve end-to-end performanceover unoptimized file operation scheduling methods. For example, theexecution system may determining that a particular file operationrequest should be divided based on identifying another file operationrequest with which part of the particular file operation request can begrouped. For example, a wildcard delete operation for deleting all filesmatching a certain criteria may be divided to separate a file operationrequest to delete files for a certain node of the external file systemin response to a determination that there is another file operationrequest for that node with which the divided request can be grouped.

In some implementations, file operation requests may include executioncriteria that may be considered by the file request manager whenperforming optimization. The execution criteria may include harddeadlines, each indicating that a file operation task must be finishedprior to the deadline, and soft deadlines, each indicating abest-to-have target time for completion of the task. For example, thefile request manager may group file operation tasks together such thatall tasks in the group may be completed before the earliest deadlineassociated with one of the file operation tasks in the group. Theexecution criteria may also include priorities, operation requirementsspecifying capabilities of a worker to execute the file operation,failure policies indicating how to handle the failure of the fileoperation task (e.g., retry, notify requestor, etc.), and/or othercriteria.

These features and additional features will be described in more detailbelow.

FIG. 1 is a block diagram of an environment 100 in which dynamicreconfiguration of a shuffle operation can occur. The environment 100includes one or more requestors 102, a file request manager 110, and oneor more data centers 150. In operation, the requestors 102 provide fileoperation requests to the file request manager 110. The file requestmanager 110 performs cluster and division operations in order to creategroups of file operation requests to send to the one or more datacenters 150. The operations associated with the file operation requestsare performed by the one or more data centers 150 on files 154 stored inassociated storage 152.

The one or more requestors 102 may be components that generate fileoperation requests associated with an external file system. In someimplementations, the requestors 102 may be applications, computingdevices, threads, and/or other components. In some implementations, therequestors 102 may communicate with the file request manager 110 over anetwork (not shown). The requestors 102 may also communicate with thefile request manager 110 by accessing methods of an applicationprogramming interface (API) associated with the file request manager110. In such an implementation, the file request manager 110 may be alibrary, or other software component running on the same computingdevice as the requestor. In some implementations, the requestors 102 maybe implemented in hardware, software, and/or a combination of the two.

The file request manager 110 may be a collection of one or more softwareprocesses running on the computing device accessible by the requestors102. In some implementations, the file request manager 110 may executeon the same computing device as a particular requestor 102. Multiplefile request managers 110 may also exist, such as, one file requestmanager 110 for each requestor 102, or one file request manager 110 fora group of requestors 102. In some implementations, the file requestmanager 110 may receive requests from the requestors 102 via a network(not shown). In such an implementation, the requests may be receivedaccording to any suitable API, including, but not limited to, HypertextTransfer Protocol (HTTP), Simple Object Access Protocol (SOAP), RemoteProcedure Call (RPC), and/or other APIs. The request may also bereceived via the requestors 102 calling methods associated with the filerequest manager 110, such as in a configuration where a requestor 102and the file request manager 110 execute on the same computing device.

As shown, the file request manager 110 includes a memory 120. The memory120 may include any type of memory or database module and may take theform of volatile and/or non-volatile memory including, withoutlimitation, magnetic media, optical media, random access memory (RAM),read-only memory (ROM), removable media, or any other suitable local orremote memory component.

The memory 120 includes file operation requests 122. In someimplementations, the file operation requests 122 are requests receivedfrom the requestors 102, and stored within a file system or database.The file operation requests 122 may include information associated withthe store requests, including, but not limited to, hard deadlines, softdeadlines, priorities, source information, target information, failurepolicies, operation requirements, and/or other information. In someimplementations, the file operation requests 122 may be indexed to allowthe other components to perform optimization. An example structure forsuch index is presented in FIG. 2, and described below.

The file request manager 110 also includes a cluster and divisionmanager 140. In operation, the cluster and division manager 140 examinesthe file operation requests 122, and determines cluster and divisionoperations to perform on the file operation requests 122 to producegroups of file operation requests to be issued to the data centers 150.For example, if the file operation requests 122 include two file copyrequests for files stored in the same one of the data centers 150, thecluster and division manager 140 may cluster these two file copyrequests into a single request and issue the request to the data center150. By clustering requests in this way, the cluster and divisionmanager 140 may reduce communication and other overhead associated withissuing the file operation requests to the data centers 150.

In some implementations, the cluster and division manager 140 may be asoftware module within the file request manager 110 that periodicallyanalyzes the file operation requests 122 in order to identify groupingopportunities. The cluster and division manager 140 may also examinefile operation requests as they are received from the requestors 102 andidentify possible grouping operations at that point. In some cases, thecluster and division manager 140 may be an external component from thefile request manager 110, such as a computing device that communicateswith the file request manager 110 over a network.

The file request manager 110 also includes a worker pool 130. The workerpool 130 includes one or more workers 132. A worker is a componentcapable of performing a file operation task by interacting with the datacenters 150. In some implementations, the worker pool 130 provides aninterface for the cluster and division manager 140 to request that aspecific file operation request be performed. The worker pool 130 maystore and manage the state of the various workers 132. For example, if aworker 132 is currently performing a file operation request, the workerpool 130 would note that the worker 132 is not available for new fileoperation requests. In some implementations, the worker pool 130receives a reference to one or more of the file operation requests 122from the cluster and division manager 140. The worker pool 130 thenselects one of the workers 132 that is available (e.g., not currentlyperforming a file operation task), and provides the worker 132 with thereference to the one or more file operation requests 122. The worker 132then retrieves information about the file operation requests 122 fromthe memory 120, and interacts with the data centers 150 to perform thefile operation requests 122.

In some implementations, the one or more workers 132 may be processes orthreads executing within the file request manager 110. The one or moreworkers 132 may be configured to interact with an appropriate datacenter 150 to perform the file operation requests 122. For example, aworker 132 may be instructed by the worker pool 130 to execute a groupof file copy requests from the file operation requests 122. The worker132 may retrieve the group of file copy requests from the memory 120,and construct a file operation request including the group of file copyrequests. In some implementations, the file operation requestconstructed by the worker 132 may be an RPC request to be sent to one ofthe one or more data centers 150. The RPC request includes necessaryinformation for each of the file copy requests in the group to allow therequest to be executed by the appropriate data center 150. Once the RPCrequest is sent, the worker 132 may wait for a response from the datacenter 150. Once the worker 132 receives the response, it may check thestatus code associated with the RPC request, and notify the requestors102 associated with the file operation requests if an error hasoccurred. The worker 132 may then inform the worker pool 130 that it isavailable to process more file operation requests. Although the aboveexample refers to the worker 132 sending an RPC request to request thatthe file operations be performed, the request to the data centers 150may be made by other mechanisms, including, but not limited to, HTTP,SOAP, File Transfer Protocol (FTP), Secure Copy (scp), Remote Shell(rsh), Remote Execute (rexec), by issuing shell commands associated withthe file operation requests directly to the data centers inimplementations in which the workers 132 are co-located with the datacenters 150, and/or other mechanisms.

In some cases, from the perspective of the requestors 102, the filerequest manager 110 may be a “black box.” A requestor 102 inserts a fileoperation task to the file request manager 110 and does not control theexecution and ordering of the task. A requestor 102 can provide metadatafor each task to guide the file request manager 110 on how and when toschedule the task.

In some implementations, each file operation request 122 is associatedwith certain metadata to describe the operation. The metadata mayinclude operation requirements describing capabilities necessary toexecute the operation. The metadata may also include a priorityindicating the urgency of the request. A higher priority task general istreated as a hint to schedule the task sooner than a lower prioritytask. The metadata may also include a deadline associated with theoperation. Two example types of deadlines are a hard deadline and softdeadline. A hard deadline means the operation must be finished beforethe given timestamp or the task is aborted. A soft deadline meanscompletion before the given timestamp is a best-to-have target, but therequestor does not expect the file request manager 110 to fail the taskif file request manager 110 cannot fulfill the task on time.

The cluster and division manager 140 may perform clustering and divisionof the file operation requests 122 per operation type. For file deletionoperations, files may be located in many of the data centers 150. Insome cases, the cluster and division manager 140 analyzes target filesassociated with the file deletion operation requests. A file deletionoperation request that contains target files on different ones of thedata centers 150 may be divided into two or more separate file deletionoperation requests so that each request contains an individual targetfile or directory. The cluster and division manager 140 may then clusterfile deletion operation requests for target files of the same datacenter in one request to reduce the overhead associated with therequest.

Regarding file copying, a file copying operation request contains asource target file and a destination location. The cluster and divisionmanager 140 may analyze the request to cluster requests that have thesame source target. The clustered requests may not necessarily have thesame destination. The requests may be clustered in such a way so thatcopying of the same file can be handled by an external copier to cachethe file on intermediate data centers hops during copy, thus reduce datatransmissions between data centers.

Regarding file merging, a file merging operation request contains a listof source files and a file merged filename. The cluster and divisionmanager 140 may analyze the requests to calculate common sublists ofrequests. A common sublist is a list of source files that are part ofmultiple requests' source file lists. The common sublists are premergedto reduce the final merging delay.

As shown, data centers 150 include storage 152 storing one or more files154. In some implementations, the data centers 150 are nodes of adistributed file system, each storing a set of files 154. The datacenters 150 may be computing devices connected to a network and mayinclude various software processes, applications, and/or daemonsoperable to handle file operation requests. In some implementations, thedata centers 150 may be configured to receive file operation requestsaccording to one or more mechanisms, including, but not limited to,HTTP, FTP, RPC, and/or other mechanisms.

FIG. 2 is a block diagram of an example index 200 of file operationrequests used for file operation request optimization. The index 200includes a priority index 202 that organizes file operation requests bypriority, and operation type index 204 that organizes file operationrequests by operation type. As shown, the priority index 202 andoperation type index 204 each include one or more lists, 206 a-c and 208a-c. Each list corresponds to a priority or operation type value, witheach operation in the list sharing the same value. For example, lists206 a includes file operation request with a priority of 100. List 208Aincludes file operation requests with operation type of “copy.” Eachfile operation request exists in exactly one of the priority lists 206a-c, and one of the operation type lists 208 a-c. File operationrequests in each priority list 208 a-c may also be sorted by a time eachrequest was received in an ascending order such that the oldest requestappears first. File operation requests with a hard deadline may belisted in the beginning of the priority lists 206 a-c, sorted by theirdeadlines in descending order such that the soonest appears first. Bysorting the priority lists 206 a-c in this way, the next file operationrequest to execute will appear first in each list.

To perform a clustering operation on the file operation requests, thecluster and division manager 140 may select the next file operationrequest 210 from the priority index 202. The cluster and divisionmanager 140 may then identify a corresponding entry 212 for the samefile operation request in the operation type index 204. The cluster anddivision manager 140 may then select the full operation type list inwhich the corresponding entry 212 appears to obtain the currentlypending file operation requests having the same operation type as thenext file operation request 210. The cluster and division manager 140may then further filter this list to obtain a group of file operationrequests to be clustered in a request for a data center 150. In someimplementations, the cluster and division manager 140 may filter thefile operation requests based on the criteria discussed previously, suchas deadline, target data center, target file, source file, and/or othercriteria.

FIG. 3 is a flow diagram of an example process 300 for file operationtask optimization through request clustering. The process 300 can beimplemented by the file request manager 110. The file request manager110 receives a plurality of file operation requests (302). In someimplementations, the file request manager 110 receives the plurality offile operation requests over a network. The file request manager 110 mayalso receive the plurality of requests via function calls performed byrequestors according to an API.

The file request manager 110 indexes the plurality of file operationrequests by priority and by operation type (304). In someimplementations, the file request manager 110 may index the plurality offile operations to create an index structure similar or identical to theindex 200 described relative to FIG. 2.

The file request manager 110 selects the next file operation requestfrom the priority index 202 (306). In some implementations, the filerequest manager 110 selects the next file operation request by selectingthe first element from the highest priority list in the priority index202. The file request manager 110 then selects other requests with thesame operation type as the type of the selected next file operation fromthe operation type index 204 (308).

The file request manager 110 then determines whether requests with thesame operation type have been found (310). In some cases, the filerequest manager 110 may make this determination based on whether theoperation type list 208 a is empty. If requests with the same operationtype are found, the file request manager 110 sends a request to a datacenter 150 corresponding to the requests to perform the group ofrequests, including the next request and the other requests (312). Insome implementations, the file request manager 110 sends the request tothe data center 150 as an RPC request including the group of requests.If no requests with the same operation type are found, the file requestmanager 110 waits for additional requests to be received of the sameoperation type as the next request (314).

FIG. 4 is a flow diagram of an example process 400 for file operationtask optimization through request clustering. The process 400 can beimplemented by the file request manager 110. The file request manager110 receives a plurality of file operation requests (402). Each fileoperation requests includes a priority, deadline in operation type, andrepresents a request to perform an operation on at least one filemaintained in a distributed file system.

The file request manager 110 identifies a group of file operationrequests to be executed from the plurality of file operation requests(404). The identification of the group of file requests is based atleast in part on at least one of: the file operations in the group offile operations being directed to a same storage system, such asdirected to the same server, data center, or physical location, or thefile operations in the group of file operation sharing a commonoperation type.

The file request manager 110 sends a request execute the group of fileoperation requests to a system configured to perform the group of fileoperation requests (406). In some implementations, the system configuredto perform the group of file operation requests may be one of the datacenters 150.

In some implementations, the file request manager 110 identifies thegroup of file operation requests to be executed together by determiningthat a particular file operation request should be divided into two ormore divided file operation requests based at least in part onidentifying a file operation request with which at least one of the twoor more divided file operation requests can be grouped. In some cases,the identification is based at least in part on at least one of: thefile operations to be grouped being directed to a same storage system,or the file operations to be grouped sharing a common operation type.The file request manager 110 may then divide the particular fileoperation request into two or more file operation requests. In somecases, the particular file operation request to be divided may be adeletion request.

In some cases, the file request manager 110 may wait an amount of timefor additional file operation requests to be received upon determiningthat the plurality of request sets do not include one or more fileoperation requests having the same operation type as the first fileoperation request. For example, if the file request manager 110 onlyidentifies a single copy request, and copy requests occur frequently,the file request manager 110 may wait for a certain amount of time inorder to receive more copy requests to group with the single copyrequest.

FIG. 5 is a block diagram of computing devices 500, 550 that may be usedto implement the systems and methods described in this document, aseither a client or as a server or plurality of servers. Computing device500 is intended to represent various forms of digital computers, such aslaptops, desktops, workstations, personal digital assistants, servers,blade servers, mainframes, and other appropriate computers. Computingdevice 550 is intended to represent various forms of mobile devices,such as personal digital assistants, cellular telephones, smartphones,and other similar computing devices. Additionally computing device 500or 550 can include Universal Serial Bus (USB) flash drives. The USBflash drives may store operating systems and other applications. The USBflash drives can include input/output components, such as a wirelesstransmitter or USB connector that may be inserted into a USB port ofanother computing device. The components shown here, their connectionsand relationships, and their functions, are meant to be exemplary only,and are not meant to limit implementations of the inventions describedand/or claimed in this document.

Computing device 500 includes a processor 502, memory 504, a storagedevice 506, a high-speed interface 508 connecting to memory 504 andhigh-speed expansion ports 510, and a low speed interface 512 connectingto low speed bus 514 and storage device 506. Each of the components 502,504, 506, 508, 510, and 512, are interconnected using various busses,and may be mounted on a common motherboard or in other manners asappropriate. The processor 502 can process instructions for executionwithin the computing device 500, including instructions stored in thememory 504 or on the storage device 506 to display graphical informationfor a GUI on an external input/output device, such as display 516coupled to high speed interface 508. In other implementations, multipleprocessors and/or multiple buses may be used, as appropriate, along withmultiple memories and types of memory. Also, multiple computing devices500 may be connected, with each device providing portions of thenecessary operations (e.g., as a server bank, a group of blade servers,or a multi-processor system).

The memory 504 stores information within the computing device 500. Inone implementation, the memory 504 is a volatile memory unit or units.In another implementation, the memory 504 is a non-volatile memory unitor units. The memory 504 may also be another form of computer-readablemedium, such as a magnetic or optical disk.

The storage device 506 is capable of providing mass storage for thecomputing device 500. In one implementation, the storage device 506 maybe or contain a computer-readable medium, such as a floppy disk device,a hard disk device, an optical disk device, or a tape device, a flashmemory or other similar solid state memory device, or an array ofdevices, including devices in a storage area network or otherconfigurations. A computer program product can be tangibly embodied inan information carrier. The computer program product may also containinstructions that, when executed, perform one or more methods, such asthose described above. The information carrier is a computer- ormachine-readable medium, such as the memory 504, the storage device 506,or memory on processor 502.

The high speed interface 508 manages bandwidth-intensive operations forthe computing device 500, while the low speed interface 512 manageslower bandwidth-intensive operations. Such allocation of functions isexemplary only. In one implementation, the high-speed interface 508 iscoupled to memory 504, display 516 (e.g., through a graphics processoror accelerator), and to high-speed expansion ports 510, which may acceptvarious expansion cards (not shown). In the implementation, low-speedinterface 512 is coupled to storage device 506 and low-speed expansionport 514. The low-speed expansion port, which may include variouscommunication ports (e.g., USB, Bluetooth, Ethernet, wireless Ethernet)may be coupled to one or more input/output devices, such as a keyboard,a pointing device, a scanner, or a networking device such as a switch orrouter, e.g., through a network adapter.

The computing device 500 may be implemented in a number of differentforms, as shown in the figure. For example, it may be implemented as astandard server 520, or multiple times in a group of such servers. Itmay also be implemented as part of a rack server system 524. Inaddition, it may be implemented in a personal computer such as a laptopcomputer 522. Alternatively, components from computing device 500 may becombined with other components in a mobile device (not shown), such asdevice 550. Each of such devices may contain one or more of computingdevice 500, 550, and an entire system may be made up of multiplecomputing devices 500, 550 communicating with each other.

Computing device 550 includes a processor 552, memory 564, aninput/output device such as a display 554, a communication interface566, and a transceiver 568, among other components. The device 550 mayalso be provided with a storage device, such as a microdrive or otherdevice, to provide additional storage. Each of the components 550, 552,564, 554, 566, and 568, are interconnected using various buses, andseveral of the components may be mounted on a common motherboard or inother manners as appropriate.

The processor 552 can execute instructions within the computing device550, including instructions stored in the memory 564. The processor maybe implemented as a chipset of chips that include separate and multipleanalog and digital processors. Additionally, the processor may beimplemented using any of a number of architectures. For example, theprocessor 552 may be a CISC (Complex Instruction Set Computers)processor, a RISC (Reduced Instruction Set Computer) processor, or anMISC (Minimal Instruction Set Computer) processor. The processor mayprovide, for example, for coordination of the other components of thedevice 550, such as control of user interfaces, applications run bydevice 550, and wireless communication by device 550.

Processor 552 may communicate with a user through control interface 558and display interface 556 coupled to a display 554. The display 554 maybe, for example, a TFT (Thin-Film-Transistor Liquid Crystal Display)display or an OLED (Organic Light Emitting Diode) display, or otherappropriate display technology. The display interface 556 may compriseappropriate circuitry for driving the display 554 to present graphicaland other information to a user. The control interface 558 may receivecommands from a user and convert them for submission to the processor552. In addition, an external interface 562 may be provided incommunication with processor 552, so as to enable near areacommunication of device 550 with other devices. External interface 562may provide, for example, for wired communication in someimplementations, or for wireless communication in other implementations,and multiple interfaces may also be used.

The memory 564 stores information within the computing device 550. Thememory 564 can be implemented as one or more of a computer-readablemedium or media, a volatile memory unit or units, or a non-volatilememory unit or units. Expansion memory 574 may also be provided andconnected to device 550 through expansion interface 572, which mayinclude, for example, a SIMM (Single In Line Memory Module) cardinterface. Such expansion memory 574 may provide extra storage space fordevice 550, or may also store applications or other information fordevice 550. Specifically, expansion memory 574 may include instructionsto carry out or supplement the processes described above, and mayinclude secure information also. Thus, for example, expansion memory 574may be provided as a security module for device 550, and may beprogrammed with instructions that permit secure use of device 550. Inaddition, secure applications may be provided via the SIMM cards, alongwith additional information, such as placing identifying information onthe SIMM card in a non-hackable manner.

The memory 564 may include, for example, flash memory and/or NVRAMmemory, as discussed below. In one implementation, a computer programproduct is tangibly embodied in an information carrier. The computerprogram product contains instructions that, when executed, perform oneor more methods, such as those described above. The information carrieris a computer- or machine-readable medium, such as the memory 564,expansion memory 574, or memory on processor 552 that may be received,for example, over transceiver 568 or external interface 562.

Device 550 may communicate wirelessly through communication interface566, which may include digital signal processing circuitry wherenecessary. Communication interface 566 may provide for communicationsunder various modes or protocols, such as GSM voice calls, SMS, EMS, orMMS messaging, CDMA, TDMA, PDC, WCDMA, CDMA2000, or GPRS, among others.Such communication may occur, for example, through radio-frequencytransceiver 568. In addition, short-range communication may occur, suchas using a Bluetooth, WiFi, or other such transceiver (not shown). Inaddition, GPS (Global Positioning System) receiver module 570 mayprovide additional navigation- and location-related wireless data todevice 550, which may be used as appropriate by applications running ondevice 550.

Device 550 may also communicate audibly using audio codec 560, which mayreceive spoken information from a user and convert it to usable digitalinformation. Audio codec 560 may likewise generate audible sound for auser, such as through a speaker, e.g., in a handset of device 550. Suchsound may include sound from voice telephone calls, may include recordedsound (e.g., voice messages, music files, etc.) and may also includesound generated by applications operating on device 550.

The computing device 550 may be implemented in a number of differentforms, as shown in the figure. For example, it may be implemented as acellular telephone 580. It may also be implemented as part of asmartphone 582, personal digital assistant, or other similar mobiledevice.

In various implementations, operations that are performed “in responseto” or “as a consequence of” another operation (e.g., a determination oran identification) are not performed if the prior operation isunsuccessful (e.g., if the determination was not performed). Operationsthat are performed “automatically” are operations that are performedwithout user intervention (e.g., intervening user input). Features inthis document that are described with conditional language may describeimplementations that are optional. In some examples, “transmitting” froma first device to a second device includes the first device placing datainto a network for receipt by the second device, but may not include thesecond device receiving the data. Conversely, “receiving” from a firstdevice may include receiving the data from a network, but may notinclude the first device transmitting the data.

“Determining” by a computing system can include the computing systemrequesting that another device perform the determination and supply theresults to the computing system. Moreover, “displaying” or “presenting”by a computing system can include the computing system sending data forcausing another device to display or present the referenced information.

Embodiments of the subject matter and the operations described in thisspecification can be implemented in digital electronic circuitry, or incomputer software, firmware, or hardware, including the structuresdisclosed in this specification and their structural equivalents, or incombinations of one or more of them. Embodiments of the subject matterdescribed in this specification can be implemented as one or morecomputer programs, i.e., one or more modules of computer programinstructions, encoded on computer storage medium for execution by, or tocontrol the operation of, data processing apparatus. Alternatively or inaddition, the program instructions can be encoded on anartificially-generated propagated signal, e.g., a machine-generatedelectrical, optical, or electromagnetic signal that is generated toencode information for transmission to suitable receiver apparatus forexecution by a data processing apparatus. A computer storage medium canbe, or be included in, a computer-readable storage device, acomputer-readable storage substrate, a random or serial access memoryarray or device, or a combination of one or more of them. Moreover,while a computer storage medium is not a propagated signal, a computerstorage medium can be a source or destination of computer programinstructions encoded in an artificially-generated propagated signal. Thecomputer storage medium can also be, or be included in, one or moreseparate physical components or media (e.g., multiple CDs, disks, orother storage devices).

The operations described in this specification can be implemented asoperations performed by a data processing apparatus on data stored onone or more computer-readable storage devices or received from othersources.

The term “data processing apparatus” encompasses all kinds of apparatus,devices, and machines for processing data, including by way of example aprogrammable processor, a computer, a system on a chip, or multipleones, or combinations, of the foregoing The apparatus can includespecial purpose logic circuitry, e.g., an FPGA (field programmable gatearray) or an ASIC (application-specific integrated circuit). Theapparatus can also include, in addition to hardware, code that createsan execution environment for the computer program in question, e.g.,code that constitutes processor firmware, a protocol stack, a databasemanagement system, an operating system, a cross-platform runtimeenvironment, a virtual machine, or a combination of one or more of them.The apparatus and execution environment can realize various differentcomputing model infrastructures, such as web services, distributedcomputing and grid computing infrastructures.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, declarative orprocedural languages, and it can be deployed in any form, including as astand-alone program or as a module, component, subroutine, object, orother unit suitable for use in a computing environment. A computerprogram may, but need not, correspond to a file in a file system. Aprogram can be stored in a portion of a file that holds other programsor data (e.g., one or more scripts stored in a markup languagedocument), in a single file dedicated to the program in question, or inmultiple coordinated files (e.g., files that store one or more modules,sub-programs, or portions of code). A computer program can be deployedto be executed on one computer or on multiple computers that are locatedat one site or distributed across multiple sites and interconnected by acommunication network.

The processes and logic flows described in this specification can beperformed by one or more programmable processors executing one or morecomputer programs to perform actions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application-specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read-only memory ora random access memory or both. The essential elements of a computer area processor for performing actions in accordance with instructions andone or more memory devices for storing instructions and data. Generally,a computer will also include, or be operatively coupled to receive datafrom or transfer data to, or both, one or more mass storage devices forstoring data, e.g., magnetic, magneto-optical disks, or optical disks.However, a computer need not have such devices. Moreover, a computer canbe embedded in another device, e.g., a mobile telephone, a personaldigital assistant (PDA), a mobile audio or video player, a game console,a Global Positioning System (GPS) receiver, or a portable storage device(e.g., a universal serial bus (USB) flash drive), to name just a few.Devices suitable for storing computer program instructions and datainclude all forms of non-volatile memory, media and memory devices,including by way of example semiconductor memory devices, e.g., EPROM,EEPROM, and flash memory devices; magnetic disks, e.g., internal harddisks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROMdisks. The processor and the memory can be supplemented by, orincorporated in, special purpose logic circuitry.

To provide for interaction with a user, embodiments of the subjectmatter described in this specification can be implemented on a computerhaving a display device, e.g., a CRT (cathode ray tube) or LCD (liquidcrystal display) monitor, for displaying information to the user and akeyboard and a pointing device, e.g., a mouse or a trackball, by whichthe user can provide input to the computer. Other kinds of devices canbe used to provide for interaction with a user as well; for example,feedback provided to the user can be any form of sensory feedback, e.g.,visual feedback, auditory feedback, or tactile feedback; and input fromthe user can be received in any form, including acoustic, speech, ortactile input. In addition, a computer can interact with a user bysending documents to and receiving documents from a device that is usedby the user; for example, by sending web pages to a web browser on auser's user device in response to requests received from the webbrowser.

Embodiments of the subject matter described in this specification can beimplemented in a computing system that includes a back-end component,e.g., as a data server, or that includes a middleware component, e.g.,an application server, or that includes a front-end component, e.g., auser computer having a graphical user interface or a Web browser throughwhich a user can interact with an implementation of the subject matterdescribed in this specification, or any combination of one or more suchback-end, middleware, or front-end components. The components of thesystem can be interconnected by any form or medium of digital datacommunication, e.g., a communication network. Examples of communicationnetworks include a local area network (“LAN”) and a wide area network(“WAN”), an inter-network (e.g., the Internet), and peer-to-peernetworks (e.g., ad hoc peer-to-peer networks).

The computing system can include users and servers. A user and serverare generally remote from each other and typically interact through acommunication network. The relationship of user and server arises byvirtue of computer programs running on the respective computers andhaving a user-server relationship to each other. In some embodiments, aserver transmits data (e.g., an HTML page) to a user device (e.g., forpurposes of displaying data to and receiving user input from a userinteracting with the user device). Data generated at the user device(e.g., a result of the user interaction) can be received from the userdevice at the server.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyinventions or of what may be claimed, but rather as descriptions offeatures specific to particular embodiments of particular inventions.Certain features that are described in this specification in the contextof separate embodiments can also be implemented in combination in asingle embodiment. Conversely, various features that are described inthe context of a single embodiment can also be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various systemcomponents in the embodiments described above should not be understoodas requiring such separation in all embodiments, and it should beunderstood that the described program components and systems cangenerally be integrated together in a single software product orpackaged into multiple software products.

Thus, particular embodiments of the subject matter have been described.Other embodiments are within the scope of the following claims. In somecases, the actions recited in the claims can be performed in a differentorder and still achieve desirable results. In addition, the processesdepicted in the accompanying figures do not necessarily require theparticular order shown, or sequential order, to achieve desirableresults. In certain implementations, multitasking and parallelprocessing may be advantageous.

What is claimed is:
 1. A computer-implemented method comprising:receiving, by a data processing apparatus, a plurality of file operationrequests, each file operation request representing a request to performan operation on at least one file maintained in a distributed filesystem and corresponding to a priority and to an operation type;selecting, by the data processing apparatus, a particular file operationrequest of the plurality of file operation requests based on thepriority of the particular file operation request relative to thepriorities of the plurality of file operation requests; in response toselecting the particular file operation request of the plurality of fileoperation requests based on the priority of the particular fileoperation request relative to the priorities of the plurality of fileoperation requests, selecting, by the data processing apparatus, a groupof file operation requests to be performed together with the particularfile operation request, the group of file operation requests having acommon operation type with the operation type of the selected particularfile operation request; and sending, by the data processing apparatus, asingle request to perform both the selected group of file operationrequests and the selected particular file operation request.
 2. Themethod of claim 1, further comprising, prior to sending the singlerequest: determining that the group of file operation requests havingthe common operation type with the operation type of the particular fileoperation request is less than a predetermined number of file operationrequests; and in response to determining that the group of fileoperation requests having the common operation type with the operationtype of the particular file operation request is less than thepredetermined number of file operation requests, waiting to receiveadditional file operation requests having the common operation type withthe operation type of the particular file operation request.
 3. Themethod of claim 1, wherein at least one file operation request of theplurality of file operation requests comprises a hard deadline.
 4. Themethod of claim 3, further comprising aborting the at least one fileoperations request of the plurality of file operation requests when theat least one file operation request is not completed by the harddeadline.
 5. The method of claim 3, wherein selecting the particularfile operation request of the plurality of file operation requests basedon the priority of the particular file operation request relative to thepriorities of the plurality of file operation requests comprises:ordering the plurality of file operation requests in ascending orderaccording to a timestamp for each file operation request in theplurality of file operation requests; promoting the at least one fileoperation request of the plurality of file operation requests includingthe hard deadline to the beginning of the order of the plurality of fileoperation requests; and selecting the highest priority request of theplurality of file operation requests as the particular file operationrequest.
 6. The method of claim 3, further comprising: identifying afile operation request that will not be completed by a soft deadlineassociated with the identified file operation request; notifying arequestor associated with the identified file operation request that theidentified file operation request will not be completed before the softdeadline; and continuing the at least one file operation request of theplurality of file operation requests with the hard deadline when theoperation associated with the identified file operation request is notcompleted by the soft deadline associated with the identified fileoperation request.
 7. The method of claim 1, further comprising:determining that a particular process associated with a file operationrequest of the plurality of file operation requests has terminated; andsending a request to execute the file operation request associated withthe particular process.
 8. The method of claim 1, wherein sending thesingle request including the group of file operation requests and theparticular file operation request further comprises sending a remoteprocedure call.
 9. The method of claim 1, wherein the operation typecomprises one or more of a file copy, a file deletion, or a file merge.10. A system comprising: one or more computers and one or more storagedevices storing instructions that are operable, when executed by the oneor more computers, to cause the one or more computers to performoperations comprising: receiving a plurality of file operation requests,each file operation request representing a request to perform anoperation on at least one file maintained in a distributed file systemand corresponding to a priority and to an operation type; selecting aparticular file operation request of the plurality of file operationrequests based on the priority of the particular file operation requestrelative to the priorities of the plurality of file operation requests;in response to selecting the particular file operation request of theplurality of file operation requests based on the priority of theparticular file operation request relative to the priorities of theplurality of file operation requests, selecting a group of fileoperation requests to be performed together with the particular fileoperation request, the group of file operation requests having a commonoperation type with the operation type of the selected particular fileoperation request; and sending a single request to perform both theselected group of file operation requests and the selected particularfile operation request.
 11. The system of claim 10, wherein theoperations further comprise, prior to sending the single request:determining that the group of file operation requests having the commonoperation type with the operation type of the particular file operationrequest is less than a predetermined number of file operation requests;and in response to determining that the group of file operation requestshaving the common operation type with the operation type of theparticular file operation request is less than the predetermined numberof file operation requests, waiting to receive additional file operationrequests having the common operation type with the operation type of theparticular file operation request.
 12. The system of claim 10, whereinat least one file operation request of the plurality of file operationrequests comprises a hard deadline.
 13. The system of claim 12, whereinthe operations further comprise aborting the at least one fileoperations request of the plurality of file operation requests when theat least one file operation request is not completed by the harddeadline.
 14. The system of claim 12, wherein selecting the particularfile operation request of the plurality of file operation requests basedon the priority of the particular file operation request relative to thepriorities of the plurality of file operation requests comprises:ordering the plurality of file operation requests in ascending orderaccording to a timestamp for each file operation request in theplurality of file operation requests; promoting the at least one fileoperation request of the plurality of file operation requests includingthe hard deadline to the beginning of the order of the plurality of fileoperation requests; and selecting the highest priority request of theplurality of file operation requests as the particular file operationrequest.
 15. The system of claim 12, wherein the operations furthercomprise identifying a file operation request that will not be completedby a soft deadline associated with the identified file operationrequest; notifying a requestor associated with the identified fileoperation request that the identified file operation request will not becompleted before the soft deadline; and continuing the at least one fileoperation request of the plurality of file operation requests with thehard deadline when the operation associated with the identified fileoperation request is not completed by the soft deadline associated withthe identified file operation request.
 16. The system of claim 10,wherein the operations further comprise: determining that a particularprocess associated with a file operation request of the plurality offile operation requests has terminated; and sending a request to executethe file operation request associated with the particular process. 17.The system of claim 10, wherein sending the single request including thegroup of file operation requests and the particular file operationrequest further comprises sending a remote procedure call.
 18. Thesystem of claim 10, wherein the operation type comprises one or more ofa file copy, a file deletion, or a file merge.
 19. A non-transitorycomputer-readable medium storing software comprising instructionsexecutable by one or more computers which, upon such execution, causethe one or more computers to perform operations comprising: receiving aplurality of file operation requests, each file operation requestrepresenting a request to perform an operation on at least one filemaintained in a distributed file system and corresponding to a priorityand to an operation type; selecting a particular file operation requestof the plurality of file operation requests based on the priority of theparticular file operation request relative to the priorities of theplurality of file operation requests; in response to selecting theparticular file operation request of the plurality of file operationrequests based on the priority of the particular file operation requestrelative to the priorities of the plurality of file operation requests,selecting a group of file operation requests to be performed togetherwith the particular file operation request, the group of file operationrequests having a common operation type with the operation type of theselected particular file operation request; and sending a single requestto perform both the selected group of file operation requests and theselected particular file operation request.
 20. The non-transitorycomputer-readable medium of claim 19, wherein the operations furthercomprise, prior to sending the single request: determining that thegroup of file operation requests having the common operation type withthe operation type of the particular file operation request is less thana predetermined number of file operation requests; and in response todetermining that the group of file operation requests having the commonoperation type with the operation type of the particular file operationrequest is less than the predetermined number of file operationrequests, waiting to receive additional file operation requests havingthe common operation type with the operation type of the particular fileoperation request.